Lubricating oils containing alkyl acrylate-vinylpyridine n-oxide copolymers



United States Patent Ofilice LUBRICATIN G OILS CON TAlNlN G ALKYL ACRYL- ATE-VINYLPYRIDINE N-QXIDE CUPQLYMERS Frederick E. Bailey, Jr., Charleston, and Walter J. Toussaint, South Charleston, W. Va., assignors to Union Carbide Corporation, acorporation of New York' No Drawing. Filed Aug. 13, 1962, Ser. No. 216,348

' 6 Claims. (Cl. 252-515) tions adapted for use in internal combustion engines is well known to those versed in this field and has resulted in substantial improvements in lubricants. However, in view of the extent to which motor transport is a dominating feature of our existence, the search for useful additives for lubricating oil com-positions is a never-ending one and hence this art is in a constant and necessary state of flux. It is with this art that this invention is primarily concerned.

The novel copolymers employed in this invention comprise as polymeric components thereof, a major amount of an ester of acrylic acid and an aliphatic alcohol containing up to 18 carbon atoms, and a minor amount of a vinylpyridine N-oxide or a lower-alkyl substituted vinylpyridine N-oxide.

, As used throughout this specification, the term loweralkyl relates to alkyl groups containing from one to six carbon atoms and in addition, the terms vinylpyridine N-oxide and loWer-alkyl substituted vinylpyridine N-oxide include both the hydrated and anhydrous forms. The dihydrate form, being more stable, is preferred. As is known in the art, the hydrated form of an amine oxide is produced by simple addition of Water, for example, merely by picking up moisture from the air.

As pointed out hereinabove, the novel copolymers employed as lubricating oil additives comprise a major amount of an ester of acrylic acid, and a minor amount ofa vinylpyridine N-oxide. The exact proportion of the components can vary over a fairly Wide range as long as the copolymer contains a solubilizing quantity of the acrylic acid ester (i.e., a sufficient quantity of acrylic acid ester to render the copolymer soluble'in the lubricating oil). A preferred proportion of the components in the copolymer is from about 85 to about 97 weight percent of acrylic acid ester and from about 3 to about 15 weight percent of the vinylpyridine N-oxide, the percentages being based upon the weight of the copolymer. A more preferred proportion is from about 88 weight percent to about 94 weight percent of acrylic acid ester and moieties have 8 or more carbon atoms in order to promote solubility of the copolymer in the lubricating oil.

Examples of alkyl acrylates which can be employed include, among others, methyl acrylate, ethyl acrylate,

propyl acrylate, isopropyl acrylate, the butyl acrylates,

the pentyl acrylates, the =hexyl acrylates, the heptyl acrylates, 2-ethylhexyl acrylate and other octyl acrylates, the decyl acrylates, the undecyl acrylates, the dodecyl acrylates, the tridecyl acrylates, the tetradecyl acrylates, the pentadecyl acrylates, the hexadecyl acrylates, the heptadecyl acrylates, the octadecyl acrylates, capyryl acrylate, laury'l acrylate, myristryl acrylate, cetyl acrylate, stearyl acrylate, and the like. If desired, methacrylic acid may be substituted for all or part of the acrylic acid.

The vinylpyridine N-oxides which can be used are vinylpyridine N-oxide, lower a-lkyl derivatives thereof wherein preferably the alkyl group has up to 6 carbon atoms, and mixtures'thereof. The vinylpyrid-ine N-oxides contemplated can be represented by Formula I:

wherein R represents either hydrogen or alkyl of up to 6 carbon atoms, and wherein X represents a number having a value in the range of from 0 to 2. Preferably, the vinyl and the R groups occupy the 2 and 5 positions on the ring, which preferred embodiment can be represented by Formula 11:

Y O XHgN Y and the dihydrate thereof, Z-methyl-S- vinylpyridine N- from about 6 to about 12 weight percent of vinylpyridine N-oxide, the percentages being based upon weight of the copolymer.

.The esters of acrylic acid employed in the formation of the novel copolymers of this invention, can be prepared by reaction ofacryl-ic acid and an alkanol or mixture of alkanols under conventional esterification conditions. The vinylpyridine N-oxides also employed in the formation of the novel copolymers of this invention, can be prepared by the processes described in U.S. Patent 2,749,349 or other methods described in the literature.

The esters of acrylic acid contemplated are the alkyl esters thereof wherein the alkyl moieties can have up to 18 carbon atoms and preferably from 8 to 18 carbon oxide and the dihydrate thereof, 2-vinyl-5-e-thylpyridine N-oxide and the dihydrate thereof, Z-isopropyl-S-vinylpyridine N-oxide and the dihydrate thereof, 2-vinyl-5- butylpyridine N-oxide and the dihydrate thereof, Z-pentyl- 5-vinylpyridine N-oxide and the dihydrate thereof, 2- hexyl-S-vinylpyridine N-oxide and the dihydrate thereof, and the like.

The copolymers employed as oil additives in the compositions of this invention may be prepared by conventional bulk, solution or dispersion methods. Preferably, the novel copolymers are prepared by reacting to 97 parts by weight of an above-described ester of acrylic acid and an alkanol with 30 to 3 parts by weight of an above-described vinylpyridine N-oxide at a temperature in the range of from 20? C. to 120 C. and preferably 40 C. to C. The above reaction can be carried out advantageously at pressures of up to 200 p.s.i., or more, although a range of atmospheric to 100 psi. is preferred. The reaction may be conducted in the presence of, for

example, 0 to 80% by Weight of an inert solvent and in atoms. It is desirable that at least a portion of the alkyl the presence of a polymerization catalyst. Among the solvents that may be employed are acetone, benzene, toluene, pentane, heptane and the like. .Among the polymerization catalysts that may be employed are diacetyl peroxide, lauryl peroxide, isopropyl percarbonate, azobisiso- Patented Jan. 19, 1965 prepared in the same manner as A and B but containing a copolymer consisting of 95 weight percent 2 -ethylhexyl acrylate and 5 weight percent Z-methyl-S-vinylpyridine N-oxide dihydrate having a reduced viscosity of 0.76, was also employed. The results are tabulated below: i

Table II Viscosity Additive Additive (percent) 100 F. 210 F. Viscosity by Index weight cs.- SUS' cs. SUS

' units units Control 46. 8 199 6. 44 V 47. 3 110 1. 6 54. 8 254 7. 95 52. 3 119 2. 4 61. 6 286 9.01 55.9 125 0. 8 51. 3 238 7. 45 50. 6 1.6 61.0 283 9. 95 55. 7 2. 4 70. 7 328 10. 5 61. 3 0.8 52. 9 246 7. 76 51. 7 1.6 65.0 301 9.77 58.5 2. 4 77. 6 359 11.78 65. 7

The following data represented by Table 111 further illustrate the outstanding behavior of the novel copolymers of this invention in respect to their carbon dispersing properties. Representative member C described above was employed as were representative additives. The dispersion test procedure comprised dispersing about 3 grams of carbon paste in 57 grams of kerosene (with or without dissolved additive) in a device providing vigorous agitation to obtain good mixing. When water was to be included, 0.3 ml. was added after the critical agitation and mixing was then continued for 1 additional minute. The carbon suspension was immediately transferred to a 50 ml. graduated cylinder (or equivalent). Observation was then made with transmitted light.

Table III Additive Percent Carbon Suspended Concentration, Additive Pegcent Dry 0.5% water Y weight 72 hrs. 144 hrs. 72 hrs. 144 hrs.

None 4s 46 56 55 Commercial Proprietary Index Improver detergent 0.4 100 100 37 36 Commercial Proprietary detergent 0.4 58 46 50 46 Commercial Proprietary detergent 0.4 50 44 52 43 Dispersant 4 C 0.4 100 100 100 103 A viscosity index improver dispersant of the polymeric methacrylate type.

A barium dinonylnaphthalene sulfonate, neutral, 50% in solvent which is extracted coastal type petroleum oil.

A sodium dinonylnaphthalene sulfonate, 50% in solvent which is extracted coastal type petroleum oil.

Additive is a copolymer of'this invention as described above.

The following data illustrate the oxidative stability of the novel copolymers of this invention using representative members (A), (B), and (C).

A proprietary-oxidation corrosion inhibitor was added throughout using Gulf Security Oil A as base stock.

2 A commercial VI improver-dispersant which is of the polymeric methacrylate type.

Another commercial VI improver-dispersant which is of the polymeric methacrylate type.

Table V.Sh ear test data for viscosity improver-dispersant V Viscosity Change, V cs. Viscosity VI Improver-Dispersant Additive Change we 216 F.

1 A commercial VI improver-dispersant which is of the polymeric methacrylate type.

As can be seen by the foregoing data, the copolymers of this invention are not only excellent viscosity index improvers but also possess excellent carbon dispersing, oxidative and shear stability properties.

This application is a continuation-in-part of application Serial No. 821,096, filed June 18, 1959, now Patent No. 3,058,959.

What is claimed is:

1. A lubricating oil which comprises a hydrocarbon lubricating oil and an amount sufiicient to improve the viscosity index and sludge dispersion of said oil of a copolymer of:

(a) an oil-solubilizing quantity of alkyl acrylate Wherein the alkyl moieties have up to 18 carbon atoms, and

(b) the remainder being a vinylpyridine N-oxide, the

said copolymer having a reduced viscosity of from about 0.2 to about 1.5 measured in a solution of 0.2 gram of copolymer per 100 milliliters of benzene at 30 C.

2. A lubricating oil which comprises a hydrocarbon lubricating oil and an amount suificient to improve the viscosity index and sludge dispersion of said oil of a copolymer of:

(a) an oil-solubilizing quantity of alkyl acrylate wherein the alkyl moieties have up to 18 carbon atoms, and

(b) the remainder being a vinylpyridine N-oxide of the formula:

wherein R represents a member of the group consisting of hydrogen and alkyl of up to 6 carbon atoms, and wherein X represents a number having a value in the range of from 0 to 2, the said copolymer'having a reduced viscosity of from about 0.2 to about 1.5 measured in a solution of 0.2 gram of copolymer per 100 milliliters of benzene at 30 C.

3. A lubricating oil which comprises a hydrocarbon lubricating oil and an amount suflicient to improve the viscosity index and sludge dispersion of said oil of a copolymer of:

(a) from about to about 97 weight percent, based on weight of said copolymer, of alkyl acrylate wherein the alkyl moieties have from 8 to 18 carbon atoms, the remainder of said copolymer being 7 (b) vinylpyridine N-oxide of the formula:

Y O 'XHzO 5 wherein one Y represents vinyl and the other Y represents a member of the group consisting of hydrogen and alkyl of up to 6 carbon atoms, and wherein, X represents a number having a value in the range of from 0 to 2, the said copolymer having a reduced viscosity in the range of from about 02 to about 1.5 measured in a solution of 0.2 gram of copolymer per 100 milli- 15 liters of benzene at 30 C.

4. The lubricating composition of claim 3 wherein said alkyl acrylate is octyl acrylate.

5. The lubricating composition of claim 3 wherein said alkyl acrylate is decyl acrylate.

6. The lubricating composition of claim 3 wherein said vinylpyridine N-oxide is 2-methyl-5-vinylpyridine N-oxide dihydrate.

References Cited in the file of this patent UNITED STATES PATENTS 2,749,349 Cislak June 5, 1956 3,030,303 Ryan Apr. 17, 1962 3,058,959 Bailey et al Oct. 16, 1962 3,062,824 Dunn et a1 Nov. 6, 1962 

1. A LUBRICATING OIL WHICH COMPRISES A HYDROCARBON LUBRICATING OIL AND AN AMOUNT SUFFICIENT TO IMPROVE THE VISCOSITY INDEX AND SLUDGE DISPERSION OF SAID OIL OF A COPOLYMER OF: (A) AN OIL-SOLUBILIZING QUANTITY OF ALKYL ACRYLATE WHEREIN THE ALKYL MOIETIES HAVE UP TO 18 CARBON ATOMS, AND (B) THE REMAINDER BEING A VINYLPYRIDINE N-OXIDE, THE SAID COPOLYMER HAVING A REDUCED VISCOSITY OF FROM ABOUT 0.2 TO ABOUT 1.5 MEASURED IN A SOLUTION OF 0.2 GRAM OF COPOLYMER PER 100 MILLILITERS OF BENZENE AT 30*C. 